Department of Clinical Chemistry, Gulhane School of Medicine, Ankara, Turkey.
Cancer Chemother Pharmacol. 2011 Aug;68(2):525-9. doi: 10.1007/s00280-010-1528-1. Epub 2010 Nov 24.
5-Fluorouracil (5-FU), acting as a pyrimidine antagonist, is a major chemotherapy drug used for the treatment of tumors such as gastrointestinal, breast, ovary, and head and neck cancers. The key and rate-limiting enzyme in 5-FU catabolism is dihydropyrimidine dehydrogenase (DHPDH), whose partial or complete deficiency exposes to a severe 5-FU toxicity in patients. The determination of DHPDH activity in patients before the treatment and setting up a personalized therapy for each patient receiving the drug can help us to prevent the possible risk of toxicity.
To isolate peripheral blood mononuclear cells (PBMCs), EDTA-anticoagulated blood samples were collected from randomly selected 47 patients and examined for 5-FU and its metabolite dihydrofluorouracil (FUH2) by using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) to observe DHPDH activity at different intervals (0 and 4th hour) indirectly.
Intra-assay and interassay CV % values of samples from the measurements of the modified methods are found 1.3-11.9, 2.3-9.4 for 5-FU and 3.1-14.4, 3.3-12.6 for FUH2, respectively. The reference values derived from 45 patients treated with 5-FU are 1.84 ± 0.34 ug/gr protein for 5-FU, 40.15 ± 11.43 ng/gr protein for FUH2, respectively. FUH2/5-FU ratio is 21.9 ± 3.72. In addition, the results determined from two patients, in which the lack of DHPDH is considered, were 3.24 and 4.16 ug/gr protein for 5-FU, 4.1 and 6.7 ng/gr protein for FUH2. FUH2/5-FU ratio is 1.26 and 1.61.
The measurements of 5-FU, FUH2, and especially their ratio (FUH2/5-FU) by the modified LC-MS/MS method could be used to determine DHPDH enzyme activity.
5-氟尿嘧啶（5-FU）作为嘧啶拮抗剂，是一种主要的化疗药物，用于治疗胃肠道、乳腺、卵巢和头颈部癌症等肿瘤。5-FU 代谢中的关键限速酶是二氢嘧啶脱氢酶（DHPDH），其部分或完全缺乏会使患者暴露于严重的 5-FU 毒性中。在治疗前测定患者的 DHPDH 活性，并为每位接受药物治疗的患者制定个性化治疗方案，可以帮助我们预防可能的毒性风险。
随机选择 47 例患者，采集 EDTA 抗凝血液样本，分离外周血单核细胞（PBMCs），采用液相色谱-串联质谱（LC-MS/MS）法检测 5-FU 及其代谢物二氢氟尿嘧啶（FUH2），间接观察不同时间点（0 和 4 小时）DHPDH 活性。
采用改良方法进行测量时，样本的批内和批间 CV%值分别为 1.3-11.9%和 2.3-9.4%，5-FU 和 FUH2 的分别为 3.1-14.4%和 3.3-12.6%。45 例接受 5-FU 治疗的患者得出的参考值分别为 5-FU 为 1.84±0.34μg/gr 蛋白，FUH2 为 40.15±11.43ng/gr 蛋白。FUH2/5-FU 比值为 21.9±3.72。此外，在两名被认为缺乏 DHPDH 的患者中，5-FU 的测定结果分别为 3.24 和 4.16μg/gr 蛋白，FUH2 为 4.1 和 6.7ng/gr 蛋白。FUH2/5-FU 比值分别为 1.26 和 1.61。
改良 LC-MS/MS 法测定 5-FU、FUH2 及其比值（FUH2/5-FU）可用于测定 DHPDH 酶活性。
